The Syrian army, reportedly backed by the Lebanese militant group Hizbollah, has dramatically escalated an attack against rebel held pockets of Homs, seeking to consolidate control of the area from Damascus to the Mediterranean coastline.

“The campaign started yesterday morning against the besieged neighborhoods in Homs Old City,” Abu Fidaa, an opposition activist speaking from inside the area told the Telegraph on Sunday.

“In the first two hours we were attacked with more than two hundred missiles. They are destroying everything. It is as if President Assad wants to burn the area.” Eyewitnesses have likened the ferocity of the attack to the bombardment against the Homs district of Baba Amr in February 2012. The attack pushed out insurgents, but also killed hundreds of civilians and destroyed the area.

A woman and two children were killed in airstrikes against the Old City and dozens more civilians wounded on Sunday, opposition activists reported.

A video posted on YouTube showed a woman running away from a destroyed home, carrying a bleeding, unconscious, child in her arms.

William Hague, the foreign secretary, condemned the onslaught: “I call upon the Assad regime to cease its brutal assault on Homs and to allow full humanitarian access to the country,” he said.

A security source in Damascus told AFP: “What’s important is to cleanse those neighbourhoods of Homs that are in the hands of armed terrorists, particularly Khaldiyeh, Hamidiyeh and the Old City.” Government troops haven’t yet succeeded in entering the areas, opposition activists told the Telegraph, but admitted that, with their supply lines cut off after the fall of Qusair, they were unlikely to be able to hold out for long.

Peter Harling from the International Crisis Group said: “If the government wants to pay the price of entering this part of Homs, meaning taking significant casualties, then the outcome is given, as was the case in Qusair.”

“The question though is how it can convert its military victories into sustainable political ones,” he added. “They haven’t been in a position to allow people back into the areas they have taken. Wherever people come back the problems [of rebel insurgents] come back with them.”